A ban on drinking water in Toledo, Ohio’s fourth-largest city, was lifted Monday after tests showed that toxins had returned to acceptable levels, city officials announced.

Hundreds of thousands of residents in the city were told not to drink tap water last week after an algae bloom in Lake Erie contaminated the water. Test results released Monday morning showed that “there are no problems whatsoever” with the drinking water, Mayor D. Michael Collins said in a televised news conference.

“Our water is safe,” Collins said. “Families can return to normal life.”

Then the mayor lifted what he said was a cup of Toledo tap water and drank.

CaptionSurrounded by algae

Haraz N. Ghanbari / Associated Press

Toledo's water intake crib, about 2.5 miles into Lake Erie. Algae may be the source of a toxin in the water.

Toledo's water intake crib, about 2.5 miles into Lake Erie. Algae may be the source of a toxin in the water. (Haraz N. Ghanbari / Associated Press)

State officials early Saturday said that an algae bloom had contaminated the city’s drinking water and Gov. John Kasich declared an emergency. Residents were told not to drink the water or use it for washing dishes or brushing teeth.

Because the contamination was from algae, authorities warned that boiling the water would actually concentrate the toxin, microsystin, making it even more dangerous to ingest. Officials said drinking the water could cause vomiting, cramps and rashes, but no serious illnesses have been reported.

With the ban lifted, officials said residents should run their taps to flush out any potentially tainted water still in their pipes. Residents were also asked not to wash cars or water lawns during an initial period of expected heavy water use.

Algae blooms are not uncommon, particularly in Lake Erie, the shallowest of the Great Lakes. Phosphorus runoff from fertilizer and animal waste can cause the algae to grow. Often the algae stays in the deeper parts of the lake, but this year shifting currents pushed it toward Maumee Bay.

The bloom was smaller than one that caused problems in 2011 for Cleveland, but the location was a problem since about 500,000 people in the Toledo area receive their drinking water through Maumee. Gov. Kasich said the state will investigate the incident to see what could be done to ease future problems.

“We were able to get through this; I know it was difficult,” Kasich said.

In July, the National Oceanic and Atmospheric Administration forecast an above-average harmful bloom of algae to spread across portions of Lake Erie by September.

“Today we clearly heard harmful algal blooms will continue to be a regular occurrence that threatens our drinking water and takes away economically crucial recreational opportunities around Lake Erie,” said Adam Rissien, director of agricultural and water policy at the Ohio Environmental Council. “Remember in 2013, 2,000 residents in Carroll Township, just east of Toledo, were ordered by public officials not to drink their tap water due to algae toxins. While this year’s bloom may not be as severe as 2011 or 2013, the threat from algae toxins is still significant. It is unacceptable that nutrient pollution has been allowed to pollute Lake Erie so significantly that we can no longer rely on having safe drinking water year-to-year without installing costly treatment options or hooking up alternative sources.”

The crisis is deeper than just one season, said Gary Fahnenstiel, a research scientist at the University of Michigan Water Center.

“The resurgence of harmful algae blooms in western Lake Erie over the last decade or so is attributable to at least three factors,” he stated. “One is the flow of phosphorus from agricultural land. The other factors that are often overlooked are climate change and invasive mussels. Climate change and the quagga and zebra mussels have changed the way Lake Erie responds to the nutrients flowing into the lake from croplands. It's not simply a nutrient story. It's more complicated than that, and it's not going to be a trivial undertaking to get rid of these harmful algal blooms.”

The International Joint Commission, an advisory agency made up of Canadian and U.S. officials, last year recommended urgent steps to reduce the amount of phosphorus applied to fields, suggesting among other things that states ban the spread of manure on frozen or snow-covered ground. That report came after a state task force in Ohio called for a 40% reduction in all forms of phosphorus going into the lake. Ohio lawmakers took a step toward tackling the algae problem when they enacted a law earlier this year requiring most farmers to undergo training before they use commercial fertilizers on their fields. But the law stopped short of mandating restrictions on farmers.

During the latest emergency, truckloads of bottled water were brought into the Toledo area and the state’s National Guard set up water purification systems to produce drinkable water.

Mayor Collins said that scientists and political leaders need to work together and figure out how to address the algae problem in Lake Erie.

“It didn't get here overnight, and we're not getting out of this overnight,” Collins told reporters.

Kent Brantly, an American doctor who contracted Ebola in West Africa while caring for victims of the disease, received an experimental serum before leaving Liberia for the U.S., the organization he works for said Sunday.

Nurse Nina Pham — once the upbeat face of the Dallas hospital that confronted the country’s first Ebola case — sued the hospital’s parent company Monday, alleging that it had failed to protect her before and after she was diagnosed with the deadly disease last fall.

With no political solution in sight, Congress faces another deadline to fund the Homeland Security Department by midnight Friday – a do-over of last week's bitter battle as Republicans try to stop President Obama's immigration plans.

Hours after Tamir Rice’s family angrily criticized Cleveland for contending in legal documents that the 12-year-old was to blame for his death at the hands of a police officer, the mayor apologized Monday and said the city would amend its court filing.